Air source heat pump refrigerant leakage detection method and air source heat pump

Abstract

The present application relates to a kind of air source heat pump refrigerant leakage detection method and air source heat pump, the detection method is calculated theoretical power by designed theoretical power model, in combination with the power deviation of actual operating power and theoretical power, the opening degree change of electronic expansion valve, the change of exhaust temperature, can realize the identification of refrigerant slight leakage, can be detected when refrigerant charge amount reduces 10%, strong identification ability;Further by combining current change, condenser inlet and outlet water temperature difference change, evaporator inlet and outlet refrigerant temperature difference change identifies obvious leakage condition, and according to different leakage degree sets different control protection measures, in the case where guaranteeing system operation safety, it realizes the progressive safety control of "early warning-limit frequency-shut down", prolongs compressor life;Wherein the designed theoretical power model fully compensates the influence of evaporation / condensation temperature change on power, reduces the false alarm of environmental change, strong against working condition interference, makes leakage more accurate.

Description

Technical Field

[0001] This invention relates to the field of air source heat pump control technology, and in particular to a method for detecting refrigerant leakage in an air source heat pump and an air source heat pump. Background Technology

[0002] Refrigerant leakage is a common and difficult-to-detect malfunction in air source heat pumps during long-term operation.

[0003] In heat pump systems, insufficient refrigerant can lead to a decrease in the system's heating / cooling capacity, excessively high compressor discharge temperature, abnormally increased power consumption, and even compressor burnout.

[0004] Existing methods for detecting refrigerant leaks mainly include measuring changes in intake / exhaust pressure using pressure sensors, observing bubbles in the sight glass, and monitoring abnormalities in condensation superheat or evaporation superheat.

[0005] Methods that use pressure sensors to measure changes in intake / exhaust pressure are highly dependent on the accuracy of the pressure sensors, are costly, and are prone to drift, which can easily lead to misjudgments.

[0006] The method of observing bubbles in the sight glass has a significant lag effect on leakage, and it is usually only detected when the leakage has become quite serious (capacity reduction of more than 20%).

[0007] Meanwhile, the above-mentioned leak detection methods also have the following drawbacks: It lacks the ability to adapt to different operating conditions and cannot distinguish between parameter fluctuations caused by refrigerant leakage and changes in environmental conditions. It cannot quantitatively assess the extent of refrigerant leakage, nor can it automatically trigger protection and control strategies. Summary of the Invention

[0008] Based on this, the purpose of this invention is to provide a method for detecting refrigerant leakage in air source heat pumps, which is based on a compressor ten-coefficient model and solves the problems of existing technologies that make it difficult to accurately identify leakage in the early stages and that leakage detection is easily affected by operating conditions.

[0009] A method for detecting refrigerant leakage in an air source heat pump includes: S1: Under stable operating conditions, obtain the actual input power of the compressor at the current moment. Condensation temperature and evaporation temperature ; and condensation temperature and evaporation temperature Substituting into the theoretical power model, the theoretical power of the compressor at the current moment is calculated. Based on the actual input power at the current moment Theoretical power To obtain the power deviation at the current moment ; S2: Obtain the current opening degree of the electronic expansion valve. Exhaust temperature Calculate the change in the electronic expansion valve at the current moment. Exhaust temperature change : If the change in the electronic expansion valve at the current moment is satisfied >0, and the change in exhaust temperature > Set safety variable threshold and power deviation Greater than the leakage power deviation threshold If so, it is determined that there is a refrigerant leak in the heat pump.

[0010] Furthermore, the theoretical power model is constructed in the following manner: SC1: Upon initial installation of the air source heat pump or under conditions confirmed to be leak-free, collect real-time operating data from multiple points under at least three typical operating conditions. The operating data includes: condensing temperature. and evaporation temperature The actual input power of the compressor ; SC2: Condensation temperature Evaporation temperature and actual input power Substitute into the AHRI standard ten-coefficient model:

[0011] SC3: Calibration of coefficients using the least squares method Thus, the calibrated theoretical power model was obtained.

[0012] Furthermore, the leakage power deviation threshold The calculation based on the theoretical power model includes the following steps: SD1: The condensation temperature at each operating point is calculated using a theoretical power model. and evaporation temperature Corresponding theoretical power , i∈(1,N), N represents the total number of working points; SD2: Actual input power based on each operating point Theoretical power Calculate the absolute value of the power deviation at each operating point. The absolute value sequence of power deviation is obtained. ; ; ; SD3: From the absolute value sequence of power deviation The largest absolute value of power deviation was selected from the samples. With the largest absolute value of power deviation Leakage power deviation threshold .

[0013] Furthermore, it also includes a threshold for leakage power deviation. Specifically: SD4: Threshold for determining leakage power deviation Is it less than or equal to the set maximum leakage power deviation? : If so, the calculated leakage power deviation threshold will be used. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. ; If not, the maximum value of the leakage power deviation. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. .

[0014] Furthermore, in step S2, if the following condition is met: the change in the electronic expansion valve at the current moment... <0, or change in exhaust temperature <Set safety variable threshold> or power deviation Less than the leakage power deviation threshold It also includes step S3: Further obtain the compressor current at the current moment Calculate the change in current at the current moment. : If the change in the electronic expansion valve at the current moment is satisfied =0, and the change in exhaust temperature >0, and the change in current If the value is less than 0, it indicates that the heat pump is leaking refrigerant.

[0015] Furthermore, in step S3, if the following condition is met: the change in the electronic expansion valve at the current moment... ≠0, or change in exhaust temperature <0, or change in current If the value is greater than 0, step S4 is also included: S4: Further obtain the current inlet water temperature Outlet water temperature evaporator refrigerant inlet temperature and evaporator refrigerant outlet temperature ; Calculate the inlet and outlet water temperature difference at the current moment. Temperature difference between refrigerant inlet and outlet Based on the current inlet and outlet water temperature difference Temperature difference between refrigerant inlet and outlet Calculate the change in water temperature difference at the current moment. Refrigerant temperature difference change : If the change in water temperature at the current moment is satisfied <0, and the change in refrigerant temperature difference If the value is less than 0, it indicates that the heat pump is leaking refrigerant. In other cases, return to step S1.

[0016] Furthermore, if the temperature difference change and refrigerant temperature difference change are both less than 0 for three consecutive sampling cycles, it is determined that the heat pump has a refrigerant leak.

[0017] Furthermore, it also includes step S5: S5: When refrigerant leakage is present: If power deviation Greater than the leakage power deviation threshold And less than 1.5 times the leakage power deviation threshold The degree of leakage was determined to be minor. If power deviation ≥1.5 times the leakage power deviation threshold The leakage level was determined to be moderate. If the heat pump is found to have a refrigerant leak according to step S4, the leak level is determined to be serious.

[0018] Furthermore, a warning will be issued for cases of minor refrigerant leakage; For cases of moderate refrigerant leakage, an early warning is issued, the compressor's maximum operating frequency is actively limited, and the compressor's maximum operating frequency is reduced by 5% in each valve adjustment cycle until the exhaust temperature drops or stabilizes. In cases of severe refrigerant leakage, the compressor will be shut down and a fault will be issued, and automatic restart of the compressor will be prohibited.

[0019] Compared to existing technologies, this invention calculates theoretical power using a designed theoretical power model. By combining the power deviation between actual operating power and theoretical power, changes in the opening of the electronic expansion valve, and changes in exhaust temperature, it can identify minor refrigerant leaks. It can detect leaks as early as 10% reduction in refrigerant charge, demonstrating strong identification capabilities and significantly earlier than the traditional superheat method (which typically requires a 20%–30% reduction). Furthermore, it identifies significant leaks by combining changes in current, condenser inlet and outlet water temperature differences, and evaporator inlet and outlet refrigerant temperature differences. Different control and protection measures are set according to different leak levels, achieving progressive safety control of "early warning-frequency limiting-shutdown" while ensuring system safety, thus extending compressor lifespan. The designed theoretical power model fully compensates for the impact of evaporation / condensation temperature changes on power, reducing false alarms due to environmental changes, and exhibiting strong resistance to operating condition interference, making leak detection more accurate. This invention utilizes only the power, current, pressure, temperature, and opening signals that the existing heat pump controller can collect, eliminating the need for additional sensors. It is easy to implement in engineering, can be directly embedded into existing heat pump main control chips without hardware modification, and is low-cost.

[0020] Meanwhile, the present invention provides an air source heat pump with a refrigerant leakage detection method, including a compressor, a four-way valve, a condenser, an electronic expansion valve, an evaporator, a parameter monitoring module, and a controller, which are circulated and connected through a refrigerant pipeline. The controller is electrically and / or communicatively connected to the compressor, the electronic expansion valve, and the parameter monitoring module, and implements the above-mentioned air source heat pump refrigerant leakage detection method.

[0021] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a flowchart of an air-source heat pump refrigerant leakage detection method according to an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. The described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0024] The air source heat pump with refrigerant leak detection proposed in this invention includes a compressor, a four-way valve, a condenser, an electronic expansion valve, an evaporator, and a parameter monitoring module, a controller, and other auxiliary pipes, all connected via refrigerant piping. The controller is electrically and / or communicatively connected to the compressor, the electronic expansion valve, and the parameter monitoring module.

[0025] The parameter monitoring module includes a power detection unit, a pressure detection unit, and a temperature detection unit.

[0026] The power detection unit is located at the AC input terminal (mains power side) of the controller and is used to collect the actual input power of the compressor. and the actual input power It is transmitted to the controller in real time.

[0027] The pressure detection unit includes a high-pressure sensor and a low-pressure sensor.

[0028] The high-pressure sensor is installed at the high-pressure inlet of the condenser to collect high-pressure data and calculate the condensing temperature based on the high-pressure data and the refrigerant saturation pressure-temperature. and condensation temperature It is transmitted to the controller in real time.

[0029] The low-pressure sensor is installed at the outlet of the evaporator to collect low-pressure data and calculate the evaporation temperature based on the low-pressure data, refrigerant saturation pressure, and temperature. and the evaporation temperature It is transmitted to the controller in real time.

[0030] The temperature detection unit includes a first temperature sensor, a second temperature sensor, a third temperature sensor, and a fourth temperature sensor.

[0031] The first temperature sensor is installed at the inlet of the condenser to collect the inlet water temperature. and the inlet water temperature It is transmitted to the controller in real time.

[0032] The second temperature sensor is installed at the outlet of the condenser to collect the outlet water temperature. and the outlet water temperature It is transmitted to the controller in real time.

[0033] The third temperature sensor is installed at the liquid inlet of the evaporator and is used to collect the refrigerant inlet temperature of the evaporator. and the refrigerant inlet temperature of the evaporator It is transmitted to the controller in real time.

[0034] The fourth temperature sensor is installed at the outlet of the evaporator and is used to collect the refrigerant outlet temperature of the evaporator. and the refrigerant outlet temperature of the evaporator It is transmitted to the controller in real time.

[0035] The controller is used to receive and store the data collected by the parameter monitoring module, and to determine the refrigerant leakage of the air source heat pump according to the set refrigerant leakage detection program.

[0036] Please see Figure 1 The controller stores a refrigerant leak detection method for air source heat pumps. The controller uses this method to determine if there is a refrigerant leak in the heat pump. The leak detection method includes the following steps: S1: Under stable operating conditions, obtain the actual input power of the compressor at the current moment. Condensation temperature and evaporation temperature ; and condensation temperature and evaporation temperature Substituting into the theoretical power model, the theoretical power of the compressor at the current moment is calculated. Based on the actual input power at the current moment Theoretical power To obtain the power deviation at the current moment .

[0037] In specific implementation, the determination of the stable operating state is as follows: SA1: Continuously collect the compressor's operating frequency and the opening degree of the electronic expansion valve within a set time period; SA2: If the change in the operating frequency of the compressor is 0 and the change rate of the opening of the electronic expansion valve is less than 1%, the heat pump system is determined to have entered a stable operating state.

[0038] The set time period is 30 seconds.

[0039] The condensation temperature at the current moment The evaporation temperature at the current moment is calculated based on the collected high-pressure and refrigerant saturation pressure-temperature data. It is calculated based on the collected low-pressure and refrigerant saturation pressure-temperature.

[0040] The power deviation at the current moment satisfy: .

[0041] The theoretical power model is constructed in the following manner: SC1: Upon initial installation of the air source heat pump or under conditions confirmed to be leak-free, collect real-time operating data from multiple points under at least three typical operating conditions. The operating data includes: condensing temperature. and evaporation temperature The actual input power of the compressor ; SC2: Condensation temperature Evaporation temperature and actual input power Substitute into the AHRI standard ten-coefficient model:

[0042] SC3: Calibration of coefficients using the least squares method Thus, the calibrated theoretical power model was obtained.

[0043] Meanwhile, the leakage power deviation threshold is calculated based on the theoretical power model calibrated above, including the following steps.

[0044] SD1: The condensation temperature at each operating point is calculated using a theoretical power model. and evaporation temperature Corresponding theoretical power , i∈(1,N), N represents the total number of working points; SD2: Actual input power based on each operating point Theoretical power Calculate the absolute value of the power deviation at each operating point. The absolute value sequence of power deviation is obtained. ; ; ; SD3: From the absolute value sequence of power deviation The largest absolute value of power deviation was selected from the samples. With the largest absolute value of power deviation Leakage power deviation threshold .

[0045] Furthermore, it also includes a threshold for leakage power deviation. Specifically, the judgment is as follows: SD4: Threshold for determining leakage power deviation Is it less than or equal to the set maximum leakage power deviation? : If so, the calculated leakage power deviation threshold will be used. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. ; If not, the maximum value of the leakage power deviation. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. .

[0046] The set maximum value of leakage power deviation Set it to 0.15~0.20.

[0047] Every 6 months of operation or after replacing the compressor / refrigerant, the theoretical power model is automatically recalibrated to eliminate deviations caused by component aging.

[0048] S2: Obtain the current opening degree of the electronic expansion valve. Exhaust temperature Calculate the change in the electronic expansion valve at the current moment. Exhaust temperature change : If the change in the electronic expansion valve at the current moment is satisfied >0, and the change in exhaust temperature > Set safety variable threshold and power deviation Greater than the leakage power deviation threshold If so, it is determined that there is a refrigerant leak in the heat pump; In other cases, proceed to step S3.

[0049] In specific implementation, the change in the electronic expansion valve at the current moment satisfy: ;in, This indicates the electron expansion aperture at the previous moment; The change in exhaust temperature at the current moment satisfy: ;in, This indicates the exhaust temperature at the previous moment.

[0050] S3: Further obtain the compressor current at the current moment. Calculate the change in current at the current moment. : If the change in the electronic expansion valve at the current moment is satisfied =0, and the change in exhaust temperature >0, and the change in current If the value is less than 0, it indicates that the heat pump is leaking refrigerant. In other cases, proceed to step S4.

[0051] In specific implementation, the change in current at the current moment satisfy: ;in, This represents the current at the previous moment.

[0052] S4: Further obtain the current inlet water temperature Outlet water temperature evaporator refrigerant inlet temperature and evaporator refrigerant outlet temperature ; Calculate the inlet and outlet water temperature difference at the current moment. Temperature difference between refrigerant inlet and outlet Based on the current inlet and outlet water temperature difference Temperature difference between refrigerant inlet and outlet Calculate the change in water temperature difference at the current moment. Refrigerant temperature difference change : If the change in water temperature at the current moment is satisfied <0, and the change in refrigerant temperature difference If the value is less than 0, it indicates that the heat pump is leaking refrigerant. In other cases, return to step S1.

[0053] In practice, the current inlet and outlet water temperature difference satisfy: ; The temperature difference between the refrigerant entering and exiting at the current moment satisfy: ; The change in water temperature at the current moment satisfy: ;in, This indicates the water temperature difference at the previous moment; The change in refrigerant temperature difference at the current moment satisfy: ;in, This indicates the temperature difference of the refrigerant at the previous moment.

[0054] Furthermore, if the temperature difference change and refrigerant temperature difference change are both less than 0 for three consecutive sampling cycles, it is determined that the heat pump has a refrigerant leak.

[0055] Furthermore, in the case of refrigerant leakage, a leakage protection mode is also included. The leakage protection mode specifically includes leakage degree classification and corresponding protection control to make the heat pump system operate more safely, and also includes step S5.

[0056] S5: When refrigerant leakage is present: If power deviation Greater than the leakage power deviation threshold And less than 1.5 times the leakage power deviation threshold ,Right now < <1.5 The leak was determined to be minor, and an early warning was issued. If power deviation ≥1.5 times the leakage power deviation threshold ,Right now ≥1.5 If the leakage level is determined to be moderate, an early warning is issued, and the compressor's maximum operating frequency is actively limited and the compressor's maximum operating frequency is reduced by 5% in each valve adjustment cycle until the exhaust temperature drops or stabilizes. If the heat pump is found to have a refrigerant leak according to step S4, the leak level is determined to be serious, the compressor is controlled to stop and a fault is output, and the compressor is prohibited from restarting automatically.

[0057] Compared to existing technologies, this invention calculates theoretical power using a designed theoretical power model. By combining the power deviation between actual operating power and theoretical power, changes in the opening of the electronic expansion valve, and changes in exhaust temperature, it can identify minor refrigerant leaks. It can detect leaks as early as 10% reduction in refrigerant charge, demonstrating strong identification capabilities and significantly earlier than the traditional superheat method (which typically requires a 20%–30% reduction). Furthermore, it identifies significant leaks by combining changes in current, condenser inlet and outlet water temperature differences, and evaporator inlet and outlet refrigerant temperature differences. Different control and protection measures are set according to different leak levels, achieving progressive safety control of "early warning-frequency limiting-shutdown" while ensuring system safety, thus extending compressor lifespan. The designed theoretical power model fully compensates for the impact of evaporation / condensation temperature changes on power, reducing false alarms due to environmental changes, and exhibiting strong resistance to operating condition interference, making leak detection more accurate. This invention utilizes only the power, current, pressure, temperature, and opening signals that the existing heat pump controller can collect, eliminating the need for additional sensors. It is easy to implement in engineering, can be directly embedded into existing heat pump main control chips without hardware modification, and is low-cost.

[0058] In practical implementation, the controller is an electronic device, which includes, but is not limited to, a memory, processor, network interface, and 4G / 5G / Wi-Fi module that can communicate with each other via a system bus. The electronic device can be a rack server, blade server, tower server, or cabinet server, or other computing equipment.

[0059] The memory includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. The memory can be an internal storage unit of the electronic device, such as the hard disk or RAM of the electronic device. The memory can also be an external storage device of the electronic device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc. The memory can also include both internal storage units and external storage devices of the electronic device.

[0060] The processor can be a central processing unit (CPU), a microcontroller, a microprocessor, or other data processing chip. This processor is typically used to control the overall operation of the electronic device, such as performing control and processing related to data interaction or communication with the electronic device. The processor is used to run program code stored in the memory or process data, for example, to run the air source heat pump refrigerant leak detection method.

[0061] The network interface may include a wireless network interface or a wired network interface, which is typically used to establish communication connections between the electronic device and other electronic devices. For example, the network interface is used to connect the electronic device to an external data platform via a network, establishing a data transmission channel and communication connection between the electronic device and the external data platform. The network may be an intranet, the Internet, Global System for Mobile communication (GSM), Wideband Code Division Multiple Access (WCDMA), 4G network, 5G network, Bluetooth, Wi-Fi, or other wireless or wired networks.

[0062] The 4G / 5G / WIFE module establishes a communication connection with the cloud platform through the network interface.

[0063] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” and “several” refer to two or more; “and / or” refers to and includes any or all possible combinations of one or more associated listed items; “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0064] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A method for detecting refrigerant leakage in an air source heat pump, characterized in that, include: S1: Under stable operating conditions, obtain the actual input power of the compressor at the current moment. Condensation temperature and evaporation temperature ; and condensation temperature and evaporation temperature Substituting into the theoretical power model, the theoretical power of the compressor at the current moment is calculated. Based on the actual input power at the current moment Theoretical power To obtain the power deviation at the current moment ; S2: Obtain the current opening degree of the electronic expansion valve. Exhaust temperature Calculate the change in the electronic expansion valve at the current moment. Exhaust temperature change : If the change in the electronic expansion valve at the current moment is satisfied >0, and the change in exhaust temperature > Set safety variable threshold and power deviation Greater than the leakage power deviation threshold If so, it is determined that there is a refrigerant leak in the heat pump.

2. The air source heat pump refrigerant leakage detection method according to claim 1, characterized in that, The theoretical power model is constructed in the following manner: SC1: Upon initial installation of the air source heat pump or under conditions confirmed to be leak-free, collect real-time operating data from multiple points under at least three typical operating conditions. The operating data includes: condensing temperature. and evaporation temperature The actual input power of the compressor ; SC2: Condensation temperature Evaporation temperature and actual input power Substitute into the AHRI standard ten-coefficient model: SC3: Calibration of coefficients using the least squares method Thus, the calibrated theoretical power model was obtained.

3. The method for detecting refrigerant leakage in an air source heat pump according to claim 2, characterized in that, The leakage power deviation threshold The calculation based on the theoretical power model includes the following steps: SD1: The condensation temperature at each operating point is calculated using a theoretical power model. and evaporation temperature Corresponding theoretical power , i∈(1,N), N represents the total number of working points; SD2: Actual input power based on each operating point Theoretical power Calculate the absolute value of the power deviation at each operating point. The absolute value sequence of power deviation is obtained. ; ； ； SD3: From the absolute value sequence of power deviation The largest absolute value of power deviation was selected from the samples. With the largest absolute value of power deviation Leakage power deviation threshold .

4. The air source heat pump refrigerant leakage detection method according to claim 3, characterized in that, It also includes a leakage power deviation threshold. Specifically: SD4: Threshold for determining leakage power deviation Is it less than or equal to the set maximum leakage power deviation? : If so, the calculated leakage power deviation threshold will be used. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. ; If not, the maximum value of the leakage power deviation. The leakage power deviation threshold for refrigerant leakage detection under actual operating conditions. .

5. The method for detecting refrigerant leakage in an air source heat pump according to claim 1, characterized in that, In step S2, if the following conditions are met: the change in the electronic expansion valve at the current moment... <0, or change in exhaust temperature <Set safety variable threshold> or power deviation Less than the leakage power deviation threshold It also includes step S3: Further obtain the compressor current at the current moment Calculate the change in current at the current moment. : If the change in the electronic expansion valve at the current moment is satisfied =0, and the change in exhaust temperature >0, and the change in current If the value is less than 0, it indicates that the heat pump is leaking refrigerant.

6. The method for detecting refrigerant leakage in an air source heat pump according to claim 5, characterized in that, In step S3, if the following conditions are met: the change in the electronic expansion valve at the current moment... ≠0, or change in exhaust temperature <0, or change in current If the value is greater than 0, step S4 is also included: S4: Further obtain the current inlet water temperature Outlet water temperature evaporator refrigerant inlet temperature and evaporator refrigerant outlet temperature ; Calculate the inlet and outlet water temperature difference at the current moment. Temperature difference between refrigerant inlet and outlet Based on the current inlet and outlet water temperature difference Temperature difference between refrigerant inlet and outlet Calculate the change in water temperature difference at the current moment. Refrigerant temperature difference change : If the change in water temperature at the current moment is satisfied <0, and the change in refrigerant temperature difference If the value is less than 0, it indicates that the heat pump is leaking refrigerant. In other cases, return to step S1.

7. The air source heat pump refrigerant leakage detection method according to claim 6, characterized in that, If the temperature difference change and refrigerant temperature difference change are both less than 0 for three consecutive sampling cycles, it is determined that there is a refrigerant leak in the heat pump.

8. The method for detecting refrigerant leakage in an air-source heat pump according to claim 6 or 7, characterized in that, It also includes step S5: S5: When refrigerant leakage is present: If power deviation Greater than the leakage power deviation threshold And less than 1.5 times the leakage power deviation threshold The degree of leakage was determined to be minor. If power deviation ≥1.5 times the leakage power deviation threshold The leakage level was determined to be moderate. If the heat pump is found to have a refrigerant leak according to step S4, the leak level is determined to be serious.

9. The method for detecting refrigerant leakage in an air source heat pump according to claim 8, characterized in that, A warning will be issued for cases of minor refrigerant leakage; For cases of moderate refrigerant leakage, an early warning is issued, the compressor's maximum operating frequency is actively limited, and the compressor's maximum operating frequency is reduced by 5% in each valve adjustment cycle until the exhaust temperature drops or stabilizes. In cases of severe refrigerant leakage, the compressor will be shut down and a fault will be issued, and automatic restart of the compressor will be prohibited.

10. An air source heat pump with a refrigerant leakage detection method, comprising a compressor, a four-way valve, a condenser, an electronic expansion valve, an evaporator, and a parameter monitoring module, and a controller, all connected via refrigerant piping, wherein the controller is electrically and / or communicatively connected to the compressor, the electronic expansion valve, and the parameter monitoring module, characterized in that... The controller implements the air source heat pump refrigerant leakage detection method as described in claims 1 to 9.

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